Analyse the roles of plants in ecosystems, and assess the impact of human activities on the balance of plants within those ecosystems;
Investigate some of the factors that affect plant growth;
Demonstrate an understanding of the structure and physiology of plants and their role in the natural environment.
Specific Expectations
Use appropriate terminology related to plants in the environment, including, but not limited to: xylem, phloem, chloroplast, pistil, stamen, nitrogen fixation, and tropism. Investigate how chemical compounds (e.g., fertilizers, herbicides, pesticides) and physical factors (e.g., amount of sun and water, quality of soil, pH of soil) affect plant growth. Investigate plant tropism by growing and observing plants in a variety of natural and human-made environments. Explain the relationship between the structure of a plant and its external environment, and describe the adaptive attributes that result in natural variation in plant structure (e.g., environmental variables cause variation in leaves within a single plant; in the Arctic, the wild crocus grows close to the ground and is covered with fine hairs). Explain the role of plant tropism (e.g., response to stimuli such as light, gravity, and humidity) in a plant’s survival.
Learning Goals
Students will develop their scientific vocabulary by using terminology related to plants in the environment.
Students will investigate various factors that affect plant growth.
Students will investigate, assess, and discuss how human impacts may influence the factors that affect plant growth.
Students will investigate and analyze adaptive attributes of plants and how this relates to the plant's external environment.
Students will understand plant tropism and explain its role in a plant's survival.
Learning Plan
Introduction
In this unit students will learn more about the world of plants. You will design and conduct experiments to determine the factors that affect seedling growth and to witness the effects of tropisms. Through research you will learn about adaptations of plants to various environments. This unit has two culminating tasks, a final unit test and a research project where you will learn about and write a report on a plant that has had a significant impact on humans.
Environmental Factors of Plant Growth
In order to survive, plants must obtain all they need from their surrounding environment. Each region on Earth has a unique range of environmental factors, including biotic factors such as the presence of diseases and competition, and abiotic factors such as levels of moisture, light, and nutrients, and range of temperature. The natural distribution of plants is determined primarily by whether a region provides the environmental conditions that meet its particular needs. Some local factors that affect plant growth:
Light levels
Soil quality
Snow cover
Competition
Pollinators
Diseases
Herbivores
Fire
Wind levels
Climate
Climate is one of the primary factors that affects plants. Climate is the average temperature and precipitation of a region. It will therefore affect the amount of light, the temperature range, and moisture available for growth. A specific climate is usually associated with a specific biome. For example, the trees of the Boreal Forest are specialized for the long dry winters found in this sub-arctic region. Other species are not able to survive under these conditions and it allows conifers to dominate the landscape. The ability for a plant to survive winter is known as its hardiness. It is a range of values that divides the country into hardiness zones. These hardiness zone values have been standardized and are included with species information. In Canada the zones range from 0 to 8. Zone 0 is the harshest environment and 8 is the zone that incorporates much of Southwestern Ontario. These zones take climate along with other factors to determine their number. Plant species grown out of zone are unlikely to survive. A plant that has a hardiness of 10 will not grow in Canada because it is not hardy enough to survive the 0 to 8 range.
Latitude and Elevation
Latitude and longitude are the values we use to determine where we are on Earth. The latitude is the measure from the equator to the North Pole and is measured in degrees, where 0° C is the equator and 90° C is the North Pole. Climate is greatly affected by latitude. Equatorial regions tend to be tropical and it is in this latitude that we find many of the world's rainforests. It is also interesting to note that this is the latitude we also find the Sahara desert. As we move northward from the equator we go fromtropical to subtropical, to temperate, to boreal, and finally totundra at the poles. The climate that is encountered in these areas is consistent worldwide and typically shares the same climatic conditions. Elevation is also a major factor that affects climate. Elevation works the same as latitude. As you go up a mountain the climate changes in the same manner as if you were heading north to the pole. Species of plants also change based on those factors.
Soil Type and Quality
There are three primary soil types found in Ontario. There is sandy soil, which is composed primarily of sand and is well draining. Clay soil contains high levels of clay and makes a dense, wet soil. Loam soil is a balanced soil that contains both sand and clay but also a high percentage of decaying organic matter that contributes to high humus content. All three types of soil compose the inorganic component of the soil, also known as the B horizon. Living plants are found in the organic layer (O horizon). When these plants die and decompose they contribute to the humus found in the decomposition layer (A horizon). As humus decomposes, itreleases nutrients back into the soil that growing plants can use; it also increases the depth of the A horizon. Soil type has an impact on the type of plants that will grow in a specific climatic region. Many plants have difficulty growing in heavy clay soils since their roots have a hard time penetrating the soil. To assist plants to grow in this soil type, home gardeners will employ various strategies. For example, they may add compost, manure, or even sand to clay soils to lighten the soil and to give it a source of nutrients as the organic matter continues to decompose. Soil from different areas may also have a wide range of soil pH. Plants have even been known to modify the soil to reduce competition and enrich the soil for their own growth. The pine tree will lose needles though its life time and as they decompose they will acidify the soil. The low pH of the soil prevents other plants from growing and enriches the soil for pine trees.
Nutrients
In humans, we talk about the need of vitamins and minerals to maintain a healthy body. Plants also have a need, but we call these micronutrients and macronutrients. The micronutrients are the nutrients that are only required in low concentrations to maintain the health of the plant. The plant consumes the macronutrients in large amounts. If plants become deficient in any of these nutrients they will show signs of the deficiency and may become stressed. Plant macronutrients include the elements carbon, oxygen, and hydrogen, which plants obtain primarily from carbon dioxide gas and water, and used in photosynthesis. The remaining macronutrients and all 8 micronutrients are obtained as dissolved ions and are usually taken up by the plant roots. Each nutrient performs vital functions in plant growth and development and when in short supply plants grow more slowly or produce fewer flowers, seeds, or roots.
Selected Macronutrients
Macronutrient
Functions
Deficiency
Comments
nitrogen
constituent of all proteins, as well as nucleic acids and chlorophyll; very important for leaf growth
chlorosis: the yellowing of old leaves due to a reduction in chlorophyll
obtained form nitrate of ammonium ions; nitrogen gas cannot be used directly by plants
potassium
involved in water balance, including the operation of stomata; required for protein synthesis
retarded growth; chlorosis of older leaves
present in large amounts in most soils but often in insoluble form
phosphorus
component of ATP, nucleic acids, phospholipids, and some proteins; critical for cell division
lack of or poor ssed and fruit development; leaves become dark and reddish; stunted growth
present mostly in fruit and seeds as well as meristematic tissue
calcium
constituent of cell walls; involved in membrane permeability
pronounced abnormalities; stunted growth, especially of roots; weakened condition
neutralizes harmful soil acids; presence can facilitate the uptake of phosphorus
magnesium
component of chlorophyll and molecules necessary for activity of some enzymes
chlorosis; sometimes reddening of leaves
enhances the uptake of phosphorus
sulfur
component of most proteins
stunted growth; yellowing of young leaves
usually plentiful in soil
In ecosystems, the types and number of plants are adapted to the climatic zone and the cycling of nutrients occurs by natural processes. In agriculture this is not the case. Within a couple of years of growing a monoculture of corn in a field, the field will become depleted of the nutrients that the plant needs for survival. This is because a monoculture is not an ecosystem and there isn't any cycling of nutrients. The farmer must replace the nutrients that are now deficient in the soil with either synthetic or natural fertilizers. Natural fertilizers are those fertilizers that are produced by the breakdown of natural materials. The best example of this is manure from livestock that can be used to fertilize crops. Synthetic fertilizers are those fertilizers that are produced by an industrial process. Most synthetic fertilizers focus on the three macronutrients needed for healthy plant growth. These are nitrogen (N), phosphorus (P), and potassium (K). We see these numbers on the packaging of fertilizer; they are known as the NPK values. These values represent a percent of the total composition of the fertilizer. For example an NPK value of 5-10-15 means that there is 5% nitrogen, 10% phosphorus, and 15% potassium; the remaining percentage is filler. These three macronutrients are important for most plant metabolic functions but each is essential for a specific plant growth: nitrogen is important for leaf growth, phosphorus for fruit growth, and potassium for stem and root growth.
Activity - Factors That Affect Plant Growth Laboratory Experiment
In this laboratory activity students will design and conduct their own experiments in partners to investigate various factors that may affect plant growth. Before students are able to participate in the lab they must complete the Pre-laboratory Quiz, achieving a grage of at least 70%. The quiz will not be counted towards their final grade, but rather used as a formative assessment to ensure students have the knowledge required to conduct the experiment. Factors That Affect Plant Growth Laboratory Experiment provides the outline and expectation of students. Students will be expected to document their progress with photographs, and will present their findings to the class in a 5 minute informal presentation after the lab submission.
Activity - Canadian Plant Adaptations Jigsaw
This activity is a great way to consolidate what students learned during the "Factors Affecting Plant Growth" portion of the unit, and to discuss for the first time how plants are adapted to particular environments where these factors vary through an inquiry-based learning activity. The Canadian Plant Adaptations Jigsaw should take place over two class periods, the first for the focus groups to work on the lesson, and the second for presenting to home groups.
Tropisms
This short video is a great introduction to tropisms, describing what they are and how they can be observed in plants.
A 'tropism' is a growth in response to a stimulus. Plants grow towards sources of water and light, which they need to survive and grow. Auxin is a plant hormone produced in the stem tips and roots, which controls the direction of growth. Plant hormones are used in weedkillers, rooting powder and to control fruit ripening. Tropisms may also be discussed in terms of positive tropism (plants move toward the stimulus) and negative tropism (plants move away from the stimulus).
There are different types of tropisms, some examples include:
Phototropism - movement or growth in response to light
Gravitropism - movement or growth in response to gravity
Chemotropism - movement or growth in response to chemicals
Thigmotropism - movement or growth in response to touch
Activity - Tropism Investigation In this laboratory activity students will conduct a Tropism Investigation to learn about the effects of light and gravity on plant growth. This will be organized for half of one class period, and revisited over a week at the beginning of class for 20 minutes to make observations and alterations as needed. This activity will be used as formative assessment.
Assessment
There will be three opportunities for assessment, the first being the completion and quality of the Factors That Affect Plant Growth Laboratory Experiment, the second being the Plant Adaptations Jigsaw, and the third being a cumulative Unit Test. The Unit Test was designed to assess all topics from the Unit.
Overall Expectations
Specific Expectations
Use appropriate terminology related to plants in the environment, including, but not limited to: xylem, phloem, chloroplast, pistil, stamen, nitrogen fixation, and tropism.
Investigate how chemical compounds (e.g., fertilizers, herbicides, pesticides) and physical factors (e.g., amount of sun and water, quality of soil, pH of soil) affect plant growth.
Investigate plant tropism by growing and observing plants in a variety of natural and human-made environments.
Explain the relationship between the structure of a plant and its external environment, and describe the adaptive attributes that result in natural variation in plant structure (e.g., environmental variables cause variation in leaves within a single plant; in the Arctic, the wild crocus grows close to the ground and is covered with fine hairs).
Explain the role of plant tropism (e.g., response to stimuli such as light, gravity, and humidity) in a plant’s survival.
Learning Goals
Students will develop their scientific vocabulary by using terminology related to plants in the environment.
Students will investigate various factors that affect plant growth.
Students will investigate, assess, and discuss how human impacts may influence the factors that affect plant growth.
Students will investigate and analyze adaptive attributes of plants and how this relates to the plant's external environment.
Students will understand plant tropism and explain its role in a plant's survival.
Learning Plan
Introduction
In this unit students will learn more about the world of plants. You will design and conduct experiments to determine the factors that affect seedling growth and to witness the effects of tropisms. Through research you will learn about adaptations of plants to various environments. This unit has two culminating tasks, a final unit test and a research project where you will learn about and write a report on a plant that has had a significant impact on humans.
Environmental Factors of Plant Growth
In order to survive, plants must obtain all they need from their surrounding environment. Each region on Earth has a unique range of environmental factors, including biotic factors such as the presence of diseases and competition, and abiotic factors such as levels of moisture, light, and nutrients, and range of temperature. The natural distribution of plants is determined primarily by whether a region provides the environmental conditions that meet its particular needs.
Some local factors that affect plant growth:
Climate
Climate is one of the primary factors that affects plants. Climate is the average temperature and precipitation of a region. It will therefore affect the amount of light, the temperature range, and moisture available for growth. A specific climate is usually associated with a specific biome. For example, the trees of the Boreal Forest are specialized for the long dry winters found in this sub-arctic region. Other species are not able to survive under these conditions and it allows conifers to dominate the landscape.
The ability for a plant to survive winter is known as its hardiness. It is a range of values that divides the country into hardiness zones. These hardiness zone values have been standardized and are included with species information. In Canada the zones range from 0 to 8. Zone 0 is the harshest environment and 8 is the zone that incorporates much of Southwestern Ontario. These zones take climate along with other factors to determine their number. Plant species grown out of zone are unlikely to survive. A plant that has a hardiness of 10 will not grow in Canada because it is not hardy enough to survive the 0 to 8 range.
Latitude and Elevation
Latitude and longitude are the values we use to determine where we are on Earth. The latitude is the measure from the equator to the North Pole and is measured in degrees, where 0° C is the equator and 90° C is the North Pole. Climate is greatly affected by
latitude. Equatorial regions tend to be tropical and it is in this latitude that we find many of the world's rainforests. It is also interesting to note that this is the latitude we also find the Sahara desert. As we move northward from the equator we go fromtropical to subtropical, to temperate, to boreal, and finally totundra at the poles. The climate that is encountered in these areas is consistent worldwide and typically shares the same climatic conditions.
Elevation is also a major factor that affects climate. Elevation works the same as latitude. As you go up a mountain the climate changes in the same manner as if you were heading north to the pole. Species of plants also change based on those factors.
Soil Type and Quality
There are three primary soil types found in Ontario. There is sandy soil, which is composed primarily of sand and is well draining. Clay soil contains high levels of clay and makes a dense, wet soil. Loam soil is a balanced soil that contains both sand and clay but also a high percentage of decaying organic matter that contributes to high humus content. All three types of soil compose the inorganic component of the soil, also known as the B horizon. Living plants are found in the organic layer (O horizon). When these plants die and decompose they contribute to the humus found in the decomposition layer (A horizon). As humus decomposes, it
Soil type has an impact on the type of plants that will grow in a specific climatic region. Many plants have difficulty growing in heavy clay soils since their roots have a hard time penetrating the soil. To assist plants to grow in this soil type, home gardeners will employ various strategies. For example, they may add compost, manure, or even sand to clay soils to lighten the soil and to give it a source of nutrients as the organic matter continues to decompose.
Soil from different areas may also have a wide range of soil pH. Plants have even been known to modify the soil to reduce competition and enrich the soil for their own growth. The pine tree will lose needles though its life time and as they decompose they will acidify the soil. The low pH of the soil prevents other plants from growing and enriches the soil for pine trees.
Nutrients
In humans, we talk about the need of vitamins and minerals to maintain a healthy body. Plants also have a need, but we call these micronutrients and macronutrients. The micronutrients are the nutrients that are only required in low concentrations to maintain the health of the plant. The plant consumes the macronutrients in large amounts. If plants become deficient in any of these nutrients they will show signs of the deficiency and may become stressed. Plant macronutrients include the elements carbon, oxygen, and hydrogen, which plants obtain primarily from carbon dioxide gas and water, and used in photosynthesis. The remaining macronutrients and all 8 micronutrients are obtained as dissolved ions and are usually taken up by the plant roots. Each nutrient performs vital functions in plant growth and development and when in short supply plants grow more slowly or produce fewer flowers, seeds, or roots.
Selected Macronutrients
In ecosystems, the types and number of plants are adapted to the climatic zone and the cycling of nutrients occurs by natural processes. In agriculture this is not the case. Within a couple of years of growing a monoculture of corn in a field, the field will become depleted of the nutrients that the plant needs for survival. This is because a monoculture is not an ecosystem and there isn't any cycling of nutrients. The farmer must replace the nutrients that are now deficient in the soil with either synthetic or natural fertilizers.
Natural fertilizers are those fertilizers that are produced by the breakdown of natural materials. The best example of this is manure from livestock that can be used to fertilize crops. Synthetic fertilizers are those fertilizers that are produced by an industrial process. Most synthetic fertilizers focus on the three macronutrients needed for healthy plant growth. These are nitrogen (N), phosphorus (P), and potassium (K). We see these numbers on the packaging of fertilizer; they are known as the NPK values. These values represent a percent of the total composition of the fertilizer. For example an NPK value of 5-10-15 means that there is 5% nitrogen, 10% phosphorus, and 15% potassium; the remaining percentage is filler. These three macronutrients are important for most plant metabolic functions but each is essential for a specific plant growth: nitrogen is important for leaf growth, phosphorus for fruit growth, and potassium for stem and root growth.
Activity - Factors That Affect Plant Growth Laboratory Experiment
In this laboratory activity students will design and conduct their own experiments in partners to investigate various factors that may affect plant growth. Before students are able to participate in the lab they must complete the Pre-laboratory Quiz, achieving a grage of at least 70%. The quiz will not be counted towards their final grade, but rather used as a formative assessment to ensure students have the knowledge required to conduct the experiment. Factors That Affect Plant Growth Laboratory Experiment provides the outline and expectation of students. Students will be expected to document their progress with photographs, and will present their findings to the class in a 5 minute informal presentation after the lab submission.
Activity - Canadian Plant Adaptations Jigsaw
This activity is a great way to consolidate what students learned during the "Factors Affecting Plant Growth" portion of the unit, and to discuss for the first time how plants are adapted to particular environments where these factors vary through an inquiry-based learning activity. The Canadian Plant Adaptations Jigsaw should take place over two class periods, the first for the focus groups to work on the lesson, and the second for presenting to home groups.
Tropisms
This short video is a great introduction to tropisms, describing what they are and how they can be observed in plants.
A 'tropism' is a growth in response to a stimulus. Plants grow towards sources of water and light, which they need to survive and grow. Auxin is a plant hormone produced in the stem tips and roots, which controls the direction of growth. Plant hormones are used in weedkillers, rooting powder and to control fruit ripening. Tropisms may also be discussed in terms of positive tropism (plants move toward the stimulus) and negative tropism (plants move away from the stimulus).
There are different types of tropisms, some examples include:Activity - Tropism Investigation
In this laboratory activity students will conduct a Tropism Investigation to learn about the effects of light and gravity on plant growth. This will be organized for half of one class period, and revisited over a week at the beginning of class for 20 minutes to make observations and alterations as needed. This activity will be used as formative assessment.
Assessment
There will be three opportunities for assessment, the first being the completion and quality of the Factors That Affect Plant Growth Laboratory Experiment, the second being the Plant Adaptations Jigsaw, and the third being a cumulative Unit Test. The Unit Test was designed to assess all topics from the Unit.
References
BBC. (2013). Controlling Plant Growth. http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway_pre_2011/living/controlplantgrowthrev1.shtml
Canadian Biodiversity Website. Canada's Ecozones. Retrieved March 7, 2013 from http://canadianbiodiversity.mcgill.ca/english/ecozones/ecozones.htm
Ministry of Education. (2008). The Ontario Curriculum: Grades 11 and 12, Science. Retrieved February 19, 2013, from http://www.edu.gov.on.ca/eng/curriculum/secondary/2009science11_12.pdf
Ontario Educational Resource Bank. (2013). SBI3C: Biology, Grade 11, College Preparation, Unit 6: Plants and the Natural Environment, Activity 8:Factors Affecting Plant Growth. Retrieved January 27, 2013 from
https://download.elearningontario.ca/repository/1246160000/SBI3CPU06/SBI3CPU06A08/content.html